a. Field of the Invention
This invention pertains to telephone transmitter cut-off devices of the type wherein interruption of the transmitter circuit is effected by moving the body of the transmitter such that at least one of the transmitter contacts is moved out of electrical conducting relation with its corresponding spring contact.
B. Prior Art
Prior art devices have accomplished telephone transmitter cut-off in a variety of ways. U.S. Pat. No. 3,588,387 discloses a transmitter cut-off device in which the transmitter is moved between a first position in which the transmitter contacts are in conducting relation with their corresponding spring contacts and a second position in which at least one of the transmitter contacts is out of conducting relation with its corresponding spring contact. This device, however, requires the use of both a biasing means and a lever arm having a cam surface to control the movement of the transmitter, and the user has to maintain constant manual contact with the lever arm during the period of transmitter cut-off.
U.S. Pat. Nos. 3,688,040, 3,699,270 and 3,731,071 disclose other transmitter cut-off devices in which an insert is disposed betwen the transmitter and the spring contacts, the insert containing a pair of conducting means which complete the connection between the spring contacts and the corresponding transmitter contacts, one of these conducting means being movable by a switch between a first position in which the circuit to the transmitter via that conducting means will be opened, and a second position in which the circuit to the transmitter will be closed.
U.S. Pat. No. 2,425,061 discloses a transmitter cut-off device in which a wafer having perforations identical to the perforations on the mouthpiece of the transmitter housing is interposed between the transmitter and the mouthpiece, the wafer being rotatable between a first position in which the perforations are aligned with those of the transmitter housing and a second position in which they are out of alignment.
U.S. Pat. No. 3,474,196 discloses a transmitter cut-off device in which a mechanical switch serves to move the center spring contact in and out of conducting relation with the corresponding transmitter contact, there being no movement of the transmitter itself.
U.S. Pat. No. 3,504,138 discloses a device in which transmitter cut-off is effectuated by rotating the body of the transmitter. A piece of insulating material is placed over a portion of the outer annular transmitter contact such that when the transmitter is rotated through the proper angle the spring contact which normally comes into contact with this outer annular transmitter contact will be moved into contact with the insulating material.
None of these prior arts systems, however, provides a low cost, simple, and efficient means to effectuate transmitter cut-off in which the user need not maintain constant manual contact with the switching means during the period of cut-off.